Connecting a landline phone to the Box

Hello, I have a little problem. I purchased a Bbox and would like to connect a landline phone to it. However, the issue is that the Box is in one room and I need the phone in another! I was told about phones with a base that you connect to the Bbox and a second handset that only needs to be connected to a power outlet. The connection would be wireless! I've found many multi-handset phones, but I can't figure out if the second handset also needs to be connected to a phone socket. Do you have any references for phones like I just mentioned? If possible, I'd like something simple, with an answering machine and the best sound quality. Budget: 80 euros max. Thank you!